Refrigerator fan motor and lamp control circuit



w. E. WILSQN 4 REFRIGERATOR FAN MOTOR AND LAMP CONTROL CIRCUIT Filed March 22, 1965 Oct. 8, 1968 INVENTOR. MLLIIIM E. Wmsou 3,405,281 Patented Oct. 8, 1968 United States Patent ice 3,405,281 REFRIGERATOR FAN MOTOR AND LAMP CONTROL CIRCUIT William E. Wilson, Detroit, Mich., assignor to American Motors Corporation, Detroit, Mich., a corporation of Maryland Filed Mar. 22, 1965, Ser. No. 441,695 2 Claims. (Cl. 307-38) ABSTRACT or THE DISCLOSURE An electrical control circuit in which the power source is in series with a lamp so that when the circuit switch is closed the lamp is illuminated and further, in which the electric motor is connected in shunt to the switch to effect energization of the motor when the switch is open.

The present invention pertains to anelectrical control circuit that is particularly adapted to refrigerators to control a fan motor and illuminating lamps within a food storage compartmennt of the refrigerator.

The present trend is to equip refrigerators with an electric motor driven fan to circulate the air about the food storage compartment and particularly to circulate the air across a cooling coil to effect its cooling. The fan motor is generally arranged in series circuit with a door actuated control switch which upon the opening of the door to the food storage compartment, and as long as the door remains open, will-hold open the circuit to the fan motor I and prevent its operation. This precaution is necessary to prevent the cold air within the compartment from being blown out through the open door. While the door is held open lamps within the compartment are energized to illuminate the compartment. The present practice is to provide a common switch to control two independent circuits, a fan motor circuit and a lamp circuit.

.This common switch is usually a double pole double throw type of a door actuated switch which will energize one or the other circuit depending upon whether the door is open or closed.

It is an object of the present invention to combine the fan motor and the lamps in a common circuit with a single pole single throw door actuated switch to effect the operation of one while the other remains inoperative.

Another object of the present invention is to arrange an impedance protected fan motor and one or more filament lamps in a series circuit with a power source whereby the fan motor is operative without illumination of the lamps and a single on-off switch is arranged in the circuit to shunt out the fan motor when the lamps are to be energized for illumination.

Other objects and advantages of the present invention will be apparent from the following description, reference being had to the accompanying drawing wherein a preferred form of the present invention is clearly shown.

In the drawing:

FIG. 1 is a side view of a refrigerator embodying the present invention with parts broken away and shown in section, and

FIG. 2 is a wiring diagram of the present invention.

Shown in the drawing is a refrigerator cabinet 10 having a food storage compartment 12. The cabinet 10 comprises an inner liner 14 whose sides are arranged in space relation from the sides of an outer shell 16 and suitable insulation material 18 placed therebetween. The liner 14 forms the walls of the compartment 12 and access is had through an opening 20 formed in the front wall 22 of the cabinet 10. The opening 20 is closed by a door 24.

The compartment 12 is cooled by a suitable refrigerating system which includes an evaporator or cooling coil 30.

The compartment 12 includes a wall or baffle 32 which forms a restricted passageway 34 and in which is provided the cooling coil 30. The passageway 34 is open at both ends to the compartment 12. In one end of the passageway is positioned a fan 36 that is operatively connected to and driven by an electric motor 38. As the fan 36 is driven it draws air from the compartment 12 into the passageway 34. The air flows over through and around the cooling coil 30 where it is cooled before returning to the compartment 12.

A plurality of vertically spaced shelves 40 are provided in the compartment 12 upon which articles to be cooled may be placed.

Lamps 42 are provided to illuminate the compartment whenever access to the compartment occurs. The lamps 42 are commercially available, and are of the incandescent or filament type adapted to be screwed into a socket 44. In the drawing the compartment is shown having two lamps, however the number may vary in accord with need or preference.

A control switch 50 is mounted in the front wall 22 of the cabinet 10 and is of the commercially available single pole single throw type having a movable actuator 52 adapted to be engaged by the door 24. The actuator 52 is arranged for contact engagement with the door 24. As the door is being swung to and held in closed position the switch will be actuated and held in open position, and as the door is swung to and held in open position the switch will be actuated to and held in closed position.

Referring to FIG. 2 the lamps 42 are connected in parallel to power supply conductors 60, 62. interposed in the line 60 is the switch 50 to control the energization and illumination of the lamps. Also interposed and connected into the line 60 in a shunt circuit around the switch 50 is the fan motor 38. A conductor 60 connects one side of the switch 50 to one side of the motor and the motors other side is connected by a conductor 66 to the opposite side of the switch 50-.

The fan motor 38 must be an impedance protected type having a relatively high resistance to current flow. One type that has proved very efficient in this circuit has a power rating between l011 watts with an operating reactance of approximately 1000 ohms. In a volt circuit this motor will provide a fan speed of approximately 2910 rpm. which adequately and efficiently circulates the air across the cooling coil.

The filament lamps 42 may be of a 40 watt power each. Though FIG. 2 illustrates that two or more lamps are to be connected in parallel circuit, tests have shown that one lamp, as of the :power of 25 watts, also functions satisfactorily. The lamp or lamps in the circuit must be of relatively low impedance in ratio to the high impedance of the fan motor. In the lamps the resistance of concern is the resistance to current flow when the lamp is cold. That is, when the current flow to the lamps is of such a low wattage that it will not cause the lamps to illuminate the lamp is considered as being cold and its resistance to current flow is relatively low. For example, a lamp of 40 watt power when cold has a resistance of approximately 28 ohms in comparison to its illuminated or hot phase when it becomes 360 ohms.

With the switch 50 in closed position the lamps are connected in direct circuit with the power supply to effect illumination. The motor 38 being in a shunt circuit and as it has a relatively higher impedance than is offered by the switch it will remain inoperative.

Opening the switch 50 will place the motor 38 in series with the power supply and in series with the parallel lamps. The motor will operate normally but the lamps 3 will not be illuminated. The impedanceo'f the its the current flow so that there is a high voltage drop across the motor to the extent that across the lamp it is low, that is in a 115 volt circuit it is approximately two volts across the lamps. This low voltage is insutficient to effect illumination of even one lamp whether 40 or 25 watts in power. The lamps will remain cold and as previously stated their resistance will be of a value to serve merely as an electrical conductor in the circuit.

From the above it will be apparent that a simple and effective circuit is provided to energize alternately a motor and a lamp or lamps. The circuit requires an inexpensive on-otf type switch and reduces wiring to a minimum. This reduction in wiring provides an economical savings in both material and labor and is greatly appreciated when the conductors 60, '62, 64, 66 are assembled into a harness arrangement 68 (see FIG. 1), and extended in a concealed manner between the walls of the cabinet. Having less wiring the service maintenance is reduced to a minimum.

Though the above description made reference to a circuit having a power source of 115 volts, 60 cycle, it has also been tried, tested and found that the same results are had where the power source is 230 volts, 5O cycle. Whichever power source is used the circuit is the same except that the motor and the lamp employed must be designed for operation for the power source selected and characterized with the impedance described.

While I have shown and described the preferred form of my invention I do not wish to limit myself to the precise details as shown but wish to avail myself of such variations and modifications as may come within the scope of the appended claims.

I claim:

1. An electrical control circuit having a power source and comprising:

a filament lamp having a relatively low impedance to the flow of current,

motor liman "electric motor' operably connected to air circulatingmeans and having a relatively high impedance,

a single pole single throw switch,

conductor means connecting in 'circuit said lamp, said switch, said power source in series to directly energize said lamp for. illumination when said switch is in closed position, and h conductor means'connecting said electric motor in said circuitin shunt to said switch to-eifect energization of said motor when said switch is in -opened position.

2. An electrical control circuit having a power source and comprising:

a plurality offilament lam'psco'nnected in parallel circuit to said power source and each filament lamp being of relatively low impedance,

a single "pole single throw switch connected in and to control said lampcircuit, I s

an electric motor operable connected to drive an air circulating device,

said electric motor being of relatively high impedance,

and

conductor means connecting said motor in said lamp circuit in a shunt circuit'to said switch and in series with said parallel connected filament lamps to energize said motor without illuminating said lamps when said switch is in open position.

References Cited UNITED STATES PATENTS 2,715,201 8/1955 Manecke 318-102 2,957,320 10/1960 Armentrout 62-264 ROBERT K. SCHAEFER, Primary Examiner. I H. HOHAUSER, Assistant Examiner. 

